After initially favoring diplomacy, US President Donald Trump resorted to an extraordinary use of force against Iran on Saturday night, striking three of the regime’s key nuclear sites.

European nations worked Monday to keep diplomatic efforts to curb the Israel-Iran war alive as the two countries traded strikes following the United States’ weekend attack on Iran’s nuclear program. Calls for Tehran to enter talks with Washington appeared to fall on deaf ears as it reached out to ally Russia for support.

It was an unprecedented attack years in the making, with some last-minute misdirection meant to give the operation a powerful element of surprise.